(a) Field of the Invention
The present invention relates to liquid crystal displays, and more specifically to a method for measuring a cell gap in a liquid crystal display.
(b) Description of the Related Art
A liquid crystal display (LCD) is one of the most widely used flat panel displays. An LCD includes two panels provided with field-generating electrodes such as pixel electrodes, and a common electrode and a liquid crystal (LC) layer interposed therebetween. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer, which determines orientations of LC molecules in the LC layer to adjust polarization of incident light.
According to a method of fabricating the LCD, alignment films for aligning the liquid crystal molecules of the liquid crystal material are coated on the two panels and are subject to alignment treatment. Spacers are spread on one of the panels, and a sealant is printed on the periphery of the panel such that the sealant has a liquid crystal injection hole. The two panels are aligned and attached to each other by hot press. A liquid crystal material is injected between the two panels through the injection hole and the injection hole is sealed, thereby forming a liquid crystal cell.
Recently, a panel assembly made of one mother glass having a plurality of liquid crystal cell areas is manufactured to improve efficiency in fabricating the LCD. The panel assembly is separated into liquid crystal cell areas by scribing the panel assembly before the injection of the liquid crystal material.
However, this process is not without drawbacks. Measuring the panel assembly or the liquid crystal cell is often difficult, as the measuring device is usually located remotely, requiring the panel or cell to be moved.
Furthermore, the fill state of the liquid crystal material is generally inspected after combining two panels in the manufacturing process of the LCD. However, even when defects in fill state are detected, it is difficult to determine the root cause, as problems with gravity-caused defects, height of interval member and the amount of the liquid crystal material all can generate such defects.